Band switching balun

ABSTRACT

A band-switching network includes a dual-band balun and a switch network. The dual-band balun includes a first output and a second output. The switch network includes a first switch and a second switch in which an input to the first switch is coupled to the first output and an input to the second switch is coupled to the second balanced output. The dual-band balun further includes a primary coil, a first secondary coil and a second secondary coil in which the first secondary coil is coupled to the first balanced output and the second secondary coil is coupled to the second balanced output. In one embodiment, the primary coil and the first secondary coil are coupled by a first coupling factor k 1 , and the primary coil and the second secondary coil are coupled by a second coupling factor k 2  that is different from the first coupling factor k 1 .

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit under 35 U.S.C. § 119(e) ofU.S. Provisional Application No. 63/034,962, filed on Jun. 4, 2020, thedisclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The subject matter disclosed herein relates to radio frequency (RF)transceivers. More particular, the subject matter disclosed hereinrelates to a dual-band balun in a transmit path and/or in a receive pathof a transceiver.

BACKGROUND

Currently, a 5^(th) Generation (5G) mmWave solution has two bands,namely 28G band (24 GHz-30 GHz) (commonly referred to and referred toherein as the low-band), and 39G band (37 GHz-40 GHz) (commonly referredto and referred to herein as the high-band). Accordingly, a typical 5Gchipset may operate in these two bands using two transmit (TX) chainsand two receive (RX) chains in which there is one TX chain and one RXchain for each band. It would be advantageous if the two bands could becovered by a footprint of a single band instead of the footprint of twobands. One approach to provide footprint of a single 24 GHz to 40 GHzband might be a wideband solution that covers both the 28G and the 39Gbands, but because a large part of the 24 GHz to 40 GHz band is not usedfor a 5G solution, such a wideband solution often ends up beingsuboptimal for the bands in question. In some cases, an additional loss(i.e., de-Q) may be added to such a wideband solution, also leading topoor performance.

SUMMARY

An example embodiment provides a band-switching network that may includea dual-band circuit and a switch network. The dual-band circuit mayinclude a first output and a second output. The switch network mayinclude a first switch and a second switch. An input to the first switchmay be coupled to the first output and an input to the second switch maybe coupled to the second output. The dual-band circuit further includesa primary coil, a first secondary coil and a second secondary coil. Thefirst secondary coil may be coupled to the first output and the secondsecondary coil may be coupled to the second output. In one embodiment,the primary coil and the first secondary coil may be coupled by a firstcoupling factor k₁, and the primary coil and the second secondary coilmay be coupled by a second coupling factor k₂ that is different from thefirst coupling factor k₁. In another embodiment, the dual-band circuitmay include a dual-band balun, and a layout of the dual-band balun mayinclude a single balun footprint.

An example embodiment provides a band-switching network that may includea dual-band circuit and a first stage of a signal-path chain. Thedual-band circuit may include a first output and a second output. Thefirst stage of the signal-path chain may include a first input and asecond input. The first output may be coupled to a first input of afirst stage of the signal-path chain, and the second output may becoupled to a second input of the first stage of the signal-path chain.In one embodiment, the dual-band circuit further includes a primarycoil, a first secondary coil and a second secondary coil in which thefirst secondary coil may be coupled to the first output and the secondsecondary coil may be coupled to the second output. In one embodiment,the first secondary coil may include a first tap for a first bias input,and the second secondary coil may include a second tap for a second biasinput. The first bias input may control a first signal path between thefirst secondary coil and the first input of the first stage of thesignal-path chain and the second bias input may control a second signalpath between the second secondary coil and the second input of the firststage of the signal-path chain. Another embodiment may include a switchnetwork that includes a first switch and a second switch. An input tothe first switch may be coupled to the first output and an input to thesecond switch may be coupled to the second output. An output of thefirst switch may be coupled to an output of the second switch.

An example embodiment provides a band-switching network that may includea dual-band circuit, a switch network and a first stage of a signalchain. The dual-band circuit may include a primary coil, a firstsecondary coil and a second secondary coil. The first secondary coil maybe coupled to a first output of the dual-band circuit and the secondsecondary coil may be coupled to a second output of the dual-bandcircuit. The switch network may include a first switch and a secondswitch. An input to the first switch may be coupled to the first outputand an input to the second switch may be coupled to the second output.An output of the first switch may be coupled to an output of the secondswitch. The first stage of a signal chain may include a first input anda second input. The first output may be coupled to a first input of afirst stage of the signal chain, and the second output may be coupled toa second input of the first stage of the signal chain.

BRIEF DESCRIPTION OF THE DRAWING

In the following section, the aspects of the subject matter disclosedherein will be described with reference to exemplary embodimentsillustrated in the figure, in which:

FIG. 1 shows a schematic diagram of an example embodiment of aband-switching network according to the subject matter disclosed herein;

FIGS. 2A and 2B respectively are graphs of an input impedance Z_(in) andan input admittance Y_(in) as a function of frequency for an examplemixer of a signal-path chain;

FIG. 3 shows an example layout of a dual-band balun, such as thedual-band balun of FIG. 1, according to the subject matter disclosedherein;

FIGS. 4A and 4B are respectively graphs of performance of theband-switching network at the 5G 28G and 39G bands in terms of S₁₁ andAC voltage gain (V_(gain) RF_(in) Mix) at the input to an TRX chain (asshown in FIG. 1) according to the subject matter disclosed herein;

FIG. 5 shows a schematic diagram of a first alternative exampleembodiment of a band-switching network according to the subject matterdisclosed herein;

FIG. 6 shows a schematic diagram of a second alternative exampleembodiment of a band-switching network according to the subject matterdisclosed herein; and

FIG. 7 depicts an electronic device that includes a band-switchingnetwork that includes a dual-band balun in a transmit path and/or areceive path of a transceiver according to the subject matter disclosedherein.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the disclosure. Itwill be understood, however, by those skilled in the art that thedisclosed aspects may be practiced without these specific details. Inother instances, well-known methods, procedures, components and circuitshave not been described in detail not to obscure the subject matterdisclosed herein.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment may beincluded in at least one embodiment disclosed herein. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” or“according to one embodiment” (or other phrases having similar import)in various places throughout this specification may not be necessarilyall referring to the same embodiment. Furthermore, the particularfeatures, structures or characteristics may be combined in any suitablemanner in one or more embodiments. In this regard, as used herein, theword “exemplary” means “serving as an example, instance, orillustration.” Any embodiment described herein as “exemplary” is not tobe construed as necessarily preferred or advantageous over otherembodiments. Additionally, the particular features, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments. Also, depending on the context of discussion herein, asingular term may include the corresponding plural forms and a pluralterm may include the corresponding singular form. Similarly, ahyphenated term (e.g., “two-dimensional,” “pre-determined,”“pixel-specific,” etc.) may be occasionally interchangeably used with acorresponding non-hyphenated version (e.g., “two dimensional,”“predetermined,” “pixel specific,” etc.), and a capitalized entry (e.g.,“Counter Clock,” “Row Select,” “PIXOUT,” etc.) may be interchangeablyused with a corresponding non-capitalized version (e.g., “counterclock,” “row select,” “pixout,” etc.). Such occasional interchangeableuses shall not be considered inconsistent with each other.

Also, depending on the context of discussion herein, a singular term mayinclude the corresponding plural forms and a plural term may include thecorresponding singular form. It is further noted that various figures(including component diagrams) shown and discussed herein are forillustrative purpose only, and are not drawn to scale. Similarly,various waveforms and timing diagrams are shown for illustrative purposeonly. For example, the dimensions of some of the elements may beexaggerated relative to other elements for clarity. Further, ifconsidered appropriate, reference numerals have been repeated among thefigures to indicate corresponding and/or analogous elements.

The terminology used herein is for the purpose of describing someexample embodiments only and is not intended to be limiting of theclaimed subject matter. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof. The terms“first,” “second,” etc., as used herein, are used as labels for nounsthat they precede, and do not imply any type of ordering (e.g., spatial,temporal, logical, etc.) unless explicitly defined as such. Furthermore,the same reference numerals may be used across two or more figures torefer to parts, components, blocks, circuits, units, or modules havingthe same or similar functionality. Such usage is, however, forsimplicity of illustration and ease of discussion only; it does notimply that the construction or architectural details of such componentsor units are the same across all embodiments or such commonly-referencedparts/modules are the only way to implement some of the exampleembodiments disclosed herein.

It will be understood that when an element or layer is referred to asbeing on, “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

The terms “first,” “second,” etc., as used herein, are used as labelsfor nouns that they precede, and do not imply any type of ordering(e.g., spatial, temporal, logical, etc.) unless explicitly defined assuch. Furthermore, the same reference numerals may be used across two ormore figures to refer to parts, components, blocks, circuits, units, ormodules having the same or similar functionality. Such usage is,however, for simplicity of illustration and ease of discussion only; itdoes not imply that the construction or architectural details of suchcomponents or units are the same across all embodiments or suchcommonly-referenced parts/modules are the only way to implement some ofthe example embodiments disclosed herein.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this subject matter belongs. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

The subject matter disclosed herein provides a band-switching networkthat includes balun having a single primary winding and two secondarywindings—all in a single transformer footprint—to switch between the 5Glow band and the high band. As used herein, the term “balun” refers to atype of transformer that is used to convert a balanced signal to anunbalanced signal or vice versa. In one embodiment, a balun may isolatea transmission line and provide a balanced output. The reduced footprintsize may provide a significant benefit in terms of area, cost ofproduction, and competitive advantage. Additionally, the reducedfootprint size, in turn, may reduce the size of the intermediatefrequency (IF) portion of a transmitter chip to be half the size of atraditional IF portion of a transmitter chip. A switching technique usedby the band-switching network disclosed herein ensures extremely littleperformance degradation over the two 5G bands in comparison to a typicalapproach that may use two separate transformers for the 5G two bands.

In an embodiment shown in FIG. 1, the subject matter disclosed hereinprovides a band-switching network that can switch between the 5G 28G andthe 39G bands by switching between the secondary coils of a mixer whileusing the same primary coil. Interaction between the coils may belimited to the primary coil interacting with only one secondary coil ata time, which provides high continuous isolation to the other secondarycoil. The secondary coil of 28G band and 39G band may include acapacitor having the same or, alternatively, different values becausethe switching network disclosed herein provides sufficient isolation.

The high isolation provided between the two secondary coils allowsindividual optimization for the bands, which leads to better performancein each of the bands. The ability to optimize the two 5G bands ofoperation as two separate networks provides an overall improvedperformance for each of the bands. In one embodiment, band-switchingnetwork disclosed herein provides a dual-band network having a highdegree of flexibility to design circuitry for each of the two bandsindependently of each other. For example, the coupling factor, secondaryinductance and the Q of the balun structure may be controlled for eachband so that various combinations of coupling factors, primary inductorsand secondary inductances.

A de-Q caused by the band-switching network disclosed herein may becontrolled by the physical sizes of the switches and may replace thede-Q typically used for input/output matching networks for a TRX chain.

FIG. 1 shows a schematic diagram of an example embodiment of aband-switching network 100 according to the subject matter disclosedherein. The band-switching network 100 may include a dual-band balun 101and a switch network 102. The dual-band balun 101 may include a singleprimary coil 101 a, a first secondary coil 101 b, and a second secondarycoil 101 c. The secondary coil 101 b may be a 5G low-band (28G)secondary coil, and the secondary coil 101 c may be a 5G high-band (39G)secondary coil. The primary coil 101 a may be common to both the 5G 28Gand 39G bands. The secondary coils 101 b and 101 c may be coupled bydifferent coupling factors k to the primary coil. For example, theprimary coil 101 a and the secondary coil 101 b may be coupled by thecoupling factor k₁, while the primary coil 101 a and the secondary coil101 c may be coupled by a different coupling factor k₂.

Switching between the two secondary coils may be provided by the switchnetwork 102. The switch network 102 may include a first double polesingle throw (DPST) switch 102 a and a second DPST switch 102 b. The twopoles of an input side of the DPST switch 102 a may be coupled to theoutput terminals of the secondary coil 101 b, and the two poles of aninput side of the DPST switch 102 b may be coupled across the outputterminals of the secondary coil 101 c. The output sides of the DPSTswitches 102 a and 102 b may be coupled to a single differential inputto a signal-path (TX or RX) chain 103, as shown in FIG. 1. For example,output sides of the DPST switches 102 a and 102 b may be coupled to aninput to a mixer, which may be represented by transistors M₁ and M₂. Thefirst and second DPST switches 102 a and 102 b may be respectivelycontrolled by control signals en_28G and en_39G.

In one embodiment, the switching network 102 may prevent the twosecondary coils 101 b and 101 c from interacting with each other (i.e.,providing isolation between the two secondary coils), thereby making itpossible for the two secondary coils to be optimized for theirrespective bands. In one embodiment, the isolation between the twosecondary coils 101 b and 101 c enables the two coils to operate in twofrequency bands that are 30-40% apart in terms of a center frequency.

Without the isolation between the two bands, the entire band-switchingnetwork 100 might act like a single entity that may not providesufficient separation between the 28 GHz and 39 GHz bands. The switchingnetwork 102 may also de-Q the band-switching network 100, therebyproviding a wide bandwidth for the 28G band, which may be useful becausethe impedance looking into the input of the signal-path chain 103 may behigh.

FIGS. 2A and 2B respectively are graphs of an input impedance Z_(in) andan input admittance Y_(in) as a function of frequency for an examplemixer of a signal-path chain. More specifically, FIG. 2A is a graph ofthe real and imaginary parts of an input impedance Z_(in) as a functionof frequency for an example mixer, whereas FIG. 2B is a graph of theresistive and capacitive values of the input admittance Y_(in) as afunction of frequency for the example mixer. The input impedance Z_(in)is to be matched to a 50 Ohm source. In FIG. 2A, the real part of theinput impedance Z_(in) as a function of frequency is indicated by curve201, and the imaginary part as a function of frequency is indicated bycurve 202. In FIG. 2B, the resistive value (in Ohms) of the inputadmittance Y_(in) is indicated by curve 203, and the capacitive value(in femtofarads (fF)) is indicated by curve 204.

As can be seen from FIGS. 2A and 2B, at the input to the example mixer,the real part of the impedance looking into the gate (Rp) may be verydifferent for the 28G band and the 39G band. This means that twodifferent transformation ratios in the balun should be used to match thebalun core to 50 Ohms. This also means that two different secondarycoils may be used while using the same primary coil.

FIG. 3 shows an example layout 300 of a dual-band balun, such as thedual-band balun 101 of FIG. 1, according to the subject matter disclosedherein. The primary coil 101 a is located between the first secondarycoil 101 b and the second secondary coil 101 c. The layout 300 of thedual-band balun 101 is capable of operating between the two 5G bandswith the assistance of switches. The inclusion of the switch network 102into, for example, the band-switching network 100, may provideadditional isolation between the two secondary coils of the balun 101.The secondary coil 101 c is tightly formed into the balun network sothat the dual-band balun 101 has the same footprint as a single-bandbalun.

Table 1 below shows some parameters associated with the dual-band balun101. Inductance of the primary coil (L_pri) and the secondary coils(L_sec) at 28 GHz and 39 GHz are shown in picohenries (pH). The changein inductive value of the primary coil may be due to the fact that thevalues are measured at two different frequencies. Also included in Table1 are the Q values for each coil (Q_pri and Q_sec). It may be seen thatthe Q for the coils does not significantly degrade in the passivenetwork. The coupling factors (k) are also shown at 28 GHz and 39 GHzare shown.

TABLE 1 Freq (GHz) L_pri (pH) L_sec (pH) Q_pri Q_sec k 28 GHz 324 809 1013 0.6 39 GHz 444 387  6 13 0.5

For a switch network 102 (FIG. 1) having, for example, a 70 μm sizeNMOS(or PMOS) device, the R_(on) is about 10 Ohms. The C_(off) for the sameexample size is 17.84 fF, which is approximately −j750 Ohms. When the28G coil is turned off, 28G coil is connected to 39G coil throughapproximately −j1500 Ohms, which is a large enough impedance tosufficiently isolate the two secondary coils.

FIGS. 4A and 4B are respectively graphs of performance of theband-switching network 100 at the 5G 28G and 39G bands in terms of S₁₁and AC voltage gain (V_(gain) RF_(in) Mix) at the input to the TRX chain103 (as shown in FIG. 1) according to the subject matter disclosedherein. FIGS. 4A and 4B show that the dual-band network provides highpassive gain and matching in both of the bands. For example, at 25.80GHz in FIG. 4A, the gain is 8.48 dB, and at 36.20 GHz, the gain is 5.69dB. The relatively lower gain in the 39 GHz plot is based on a lowergate impedance at 39 GHz (as shown in FIG. 2B).

FIG. 5 shows a schematic diagram of a first alternative exampleembodiment of a band-switching network 500 according to the subjectmatter disclosed herein. The band-switching network 500 may include adual-band balun 501 that is coupled to the input to a TRX chain 503.

The dual-band balun 501 may include a single primary coil 501 a, a firstsecondary coil 501 b, and a second secondary coil 501 c. The secondarycoil 501 b may be a low-band (28G) secondary coil, and the secondarycoil 501 c may be a high-band (39G) secondary coil. The primary coil 501a may be common to both the 5G 28G and 39G bands. The secondary coils101 b and 101 c may be coupled by different coupling factors k to theprimary coil. For example, the primary coil 501 a and the secondary coil501 b may be coupled by the coupling factor k₁, while the primary coil501 a and the secondary coil 501 c may be coupled by a differentcoupling factor k₂.

The first and second secondary coils 501 b and 501 c may include a tapthrough which a bias voltage (V_(bias) 28G and V_(bias) 39G) may beapplied to control selection of the signal path that passes through thecorresponding coil. As shown in FIG. 5, the outputs of first and secondsecondary coils 501 a and 501 b are respectively coupled to a firsttransconductance pair 503 a, which includes transistors M₁ and M₂, andto a second transconductance pair 503 b, which includes transistors M₃and M₄. The outputs of the first and second transconductance amplifiersare coupled together as part of the TRX chain 503.

In one embodiment, the topology of the band-switching network 500 maynot provide the same degree of band separation as the topology of theband-switching network 100 (FIG. 1), but may be useful in technologiesin which the change in input impedance is highly dependent on the inputbias. Another consideration associated with the topology of theband-switching network 500 is that two secondary coils 501 b and 501 care eventually coupled through the gate-to-drain capacitance C_(gd) ofthe respective transconductance pairs. The C_(gd) for physically largerTRX chains may be relatively large and may provide relatively lowimpedance paths between the secondary coils, particularly at mmWavefrequencies.

FIG. 6 shows a schematic diagram of a second alternative exampleembodiment of a band-switching network 600 according to the subjectmatter disclosed herein. The band-switching network 600 may include adual-band balun 601 that is coupled to the input to a TRX chain 603,represented by transconductance pairs 603 a and 603 b. The outputs ofthe transconductance pairs 603 a and 603 b TRX chain are coupled to aswitch network 602.

The dual-band balun 601 may include a single primary coil 601 a, a firstsecondary coil 601 b, and a second secondary coil 601 c. The secondarycoil 601 b may be a low-band (28G) secondary coil, and the secondarycoil 601 c may be a high-band (39G) secondary coil. The primary coil 601a may be common to both the 5G 28G and 39G bands. The secondary coils601 b and 601 c may be coupled by different coupling factors k to theprimary coil. For example, the primary coil 601 a and the secondary coil601 b may be coupled by the coupling factor k₁, while the primary coil601 a and the secondary coil 601 c may be coupled by a differentcoupling factor k₂.

The first and secondary coils 601 b and 601 c may include a tap throughwhich a bias voltage (V_(bias) 28G and V_(bias) 39G) may be applied tocontrol selection of the signal path that passes through the coil. Theoutputs of first and second secondary coils 601 a and 601 b arerespectively coupled to the first transconductance pair 603 a, whichincludes transistors M₁ and M₂, and to a second transconductance pair603 b, which includes M₃ and M₄.

The switch network 602 may include a first double pole single throw(DPST) switch 602 a and a second DPST switch 602 b. The two poles of aninput side of the DPST switch 602 a are connected to the drain terminalsof the transistors M₁ and M₂ of the transconductance pair 603 a. The twopoles of an input side of the DPST switch 602 b are connected to thedrain terminals of the transistors M₃ and M₄ of the transconductancepair 603 b. The output sides of the DPST switches 602 a and 602 b areconnected are connected together, as shown in FIG. 6. The first andsecond DPST switches 602 a and 602 b are respectively controlled bycontrol signals en_28G and en_39G. The isolation in the drain-combiningstructure within the TRX chain 603 may be improved by the switch network602 in comparison to the isolation in the drain-combining structure withthe TRX chain 503 in FIG. 5.

FIG. 7 depicts an electronic device 700 that includes a band-switchingnetwork that includes a dual-band balun in a transmit path and/or areceive path of a transceiver according to the subject matter disclosedherein. Electronic device 700 may be used in, but not limited to, acomputing device, a personal digital assistant (PDA), a laptop computer,a mobile computer, a web tablet, a wireless phone, a cell phone, a smartphone, a digital music player, or a wireline or wireless electronicdevice. The electronic device 700 may also be part of, but not limitedto, an ADAS, a mobile-device imaging system, an industrial imagingsystem, robotics, etc. The electronic device 700 may include acontroller 710, an input/output device 720 such as, but not limited to,a keypad, a keyboard, a display, a touch-screen display, a camera,and/or an image sensor, a memory 730, an interface 740, a GPU 750, andan imaging processing unit 760 that are coupled to each other through abus 770. The controller 710 may include, for example, at least onemicroprocessor, at least one digital signal processor, at least onemicrocontroller, or the like. The memory 730 may be configured to storea command code to be used by the controller 710 or a user data.

Electronic device 700 and the various system components of electronicdevice 700 may include the image processing unit 760. The interface 740may be configured to include a wireless interface that is configured totransmit data to or receive data from a wireless communication networkusing a RF signal. The wireless interface 740 may include, for example,an antenna, a wireless transceiver and so on. In one embodiment, theinterface 740 may include a band-switching network that includes adual-band balun in a transmit path and/or a receive path of atransceiver according to the subject matter disclosed herein. Theelectronic system 700 also may be used in a communication interfaceprotocol of a communication system, such as, but not limited to, CodeDivision Multiple Access (CDMA), Global System for Mobile Communications(GSM), North American Digital Communications (NADC), Extended TimeDivision Multiple Access (E-TDMA), Wideband CDMA (WCDMA), CDMA2000,Wi-Fi, Municipal Wi-Fi (Muni Wi-Fi), Bluetooth, Digital EnhancedCordless Telecommunications (DECT), Wireless Universal Serial Bus(Wireless USB), Fast low-latency access with seamless handoff OrthogonalFrequency Division Multiplexing (Flash-OFDM), IEEE 802.20, GeneralPacket Radio Service (GPRS), iBurst, Wireless Broadband (WiBro), WiMAX,WiMAX-Advanced, Universal Mobile Telecommunication Service-Time DivisionDuplex (UMTS-TDD), High Speed Packet Access (HSPA), Evolution DataOptimized (EVDO), Long Term Evolution-Advanced (LTE-Advanced),Multichannel Multipoint Distribution Service (MMDS), and so forth.

Embodiments of the subject matter and the operations described in thisspecification may be implemented in digital electronic circuitry, or incomputer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. Embodiments of the subject matterdescribed in this specification may be implemented as one or morecomputer programs, i.e., one or more modules of computer-programinstructions, encoded on computer-storage medium for execution by, or tocontrol the operation of, data-processing apparatus. Alternatively or inaddition, the program instructions can be encoded on anartificially-generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal, that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer-storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial-access memoryarray or device, or a combination thereof. Moreover, while acomputer-storage medium is not a propagated signal, a computer-storagemedium may be a source or destination of computer-program instructionsencoded in an artificially-generated propagated signal. Thecomputer-storage medium can also be, or be included in, one or moreseparate physical components or media (e.g., multiple CDs, disks, orother storage devices). Additionally, the operations described in thisspecification may be implemented as operations performed by adata-processing apparatus on data stored on one or morecomputer-readable storage devices or received from other sources.

While this specification may contain many specific implementationdetails, the implementation details should not be construed aslimitations on the scope of any claimed subject matter, but rather beconstrued as descriptions of features specific to particularembodiments. Certain features that are described in this specificationin the context of separate embodiments may also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment may also beimplemented in multiple embodiments separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination may in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular embodiments of the subject matter have been describedherein. Other embodiments are within the scope of the following claims.In some cases, the actions set forth in the claims may be performed in adifferent order and still achieve desirable results. Additionally, theprocesses depicted in the accompanying figures do not necessarilyrequire the particular order shown, or sequential order, to achievedesirable results. In certain implementations, multitasking and parallelprocessing may be advantageous.

As will be recognized by those skilled in the art, the innovativeconcepts described herein may be modified and varied over a wide rangeof applications. Accordingly, the scope of claimed subject matter shouldnot be limited to any of the specific exemplary teachings discussedabove, but is instead defined by the following claims.

What is claimed is:
 1. A band-switching network, comprising: a dual-bandcircuit comprising a first output and a second output, a primary coil, afirst secondary coil coupled to the first output and a second secondarycoil coupled to the second output, the primary coil and the firstsecondary coil being coupled by a first coupling factor k1, and theprimary coil and the second secondary coil being coupled by a secondcoupling factor k2 that is different from the first coupling factor k1;and a switch network comprising a first switch and a second switch, aninput to the first switch being coupled to the first output and an inputto the second switch being coupled to the second output.
 2. Theband-switching network of claim 1, wherein the dual-band circuitcomprises a dual-band balun, and wherein a layout of the dual-band baluncomprises a single balun footprint.
 3. The band-switching network ofclaim 1, wherein a frequency band of the first output comprises a FifthGeneration (5G) 28G band, and a frequency band of the second outputcomprises a 5G 39G band.
 4. The band-switching network of claim 3,wherein an output of the first switch is coupled to an output of thesecond switch.
 5. The band-switching network of claim 1, wherein thefirst output is coupled to a first input of a signal-path chain, and afirst output of the signal-path chain is coupled to the input to thefirst switch, and wherein the second output is coupled to a second inputof the signal-path chain, and a second output of the signal-path chainis coupled to the input of the second switch.
 6. The band-switchingnetwork of claim 5, wherein the first secondary coil includes a firsttap for a first bias input, and the second secondary coil includes asecond tap for a second bias input, the first bias input controlling afirst signal path between the first secondary coil and the first inputof the signal-path chain and the second bias input controlling a secondsignal path between the second secondary coil and the second input ofthe signal-path chain.
 7. The band-switching network of claim 1, whereina layout of first secondary coil is located within a layout of theprimary coil, and wherein the layout of the primary coil is locatedwithin a layout of the second secondary coil.
 8. A band-switchingnetwork, comprising: a dual-band circuit comprising a first output and asecond output, a primary coil, a first secondary coil coupled to thefirst output and a second secondary coil coupled to the second output,the primary coil and the first secondary coil being coupled by a firstcoupling factor k1, and the primary coil and the second secondary coilbeing coupled by a second coupling factor k2 that is different from thefirst coupling factor k1; and a signal-path chain comprising a firstinput and a second input, the first output being coupled to a firstinput of the signal-path chain, and the second output being coupled to asecond input of the signal-path chain.
 9. The band-switching network ofclaim 8, wherein the dual-band circuit comprises a dual-band balun, andwherein a layout of the dual-band balun comprises a single balunfootprint.
 10. The band-switching network of claim 9, wherein afrequency band of the first output comprises a Fifth Generation (5G) 28Gband, and a frequency band of the second output comprises a 5G 39G band.11. The band-switching network of claim 8, wherein the first secondarycoil includes a first tap for a first bias input, and the secondsecondary coil includes a second tap for a second bias input, the firstbias input controlling a first signal path between the first secondarycoil and the first input of the signal-path chain and the second biasinput controlling a second signal path between the second secondary coiland the second input of the signal-path chain.
 12. The band-switchingnetwork of claim 11, further comprising a switch network comprising afirst switch and a second switch, an input to the first switch beingcoupled to the first output and an input to the second switch beingcoupled to the second output, an output of the first switch beingcoupled to an output of the second switch.
 13. The band-switchingnetwork of claim 7, wherein a layout of first secondary coil is locatedwithin a layout of the primary coil, and wherein the layout of theprimary coil is located within a layout of the second secondary coil.14. A band-switching network, comprising: a dual-band circuit comprisinga primary coil, a first secondary coil and a second secondary coil, thefirst secondary coil being coupled to a first output of the dual-bandcircuit and the second secondary coil being coupled to a second outputof the dual-band circuit, the primary coil and the first secondary coilbeing coupled by a first coupling factor k1, and the primary coil andthe second secondary coil being coupled by a second coupling factor k2that is different from the first coupling factor k1; a switch networkcomprising a first switch and a second switch, an input to the firstswitch being coupled to the first output and an input to the secondswitch being coupled to the second output, an output of the first switchbeing coupled to an output of the second switch; and a signal chaincomprising a first input and a second input, the first output beingcoupled to a first input of the signal chain, and the second outputbeing coupled to a second input of the signal chain.
 15. Theband-switching network of claim 14, wherein the dual-band circuitcomprises a dual-band balun, and wherein a layout of the dual-band baluncomprises a single balun footprint.
 16. The band-switching network ofclaim 15, wherein a frequency band of the first output comprises a FifthGeneration (5G) 28G band, and a frequency band of the second outputcomprises a 5G 39G band.
 17. The band-switching network of claim 16,wherein the first secondary coil includes a first tap for a first biasinput, and the second secondary coil includes a second tap for a secondbias input, the first bias input controlling a first signal path betweenthe first secondary coil and the first input of the signal chain and thesecond bias input controlling a second signal path between the secondsecondary coil and the second input of the signal chain.
 18. Theband-switching network of claim 14, wherein a layout of first secondarycoil is located within a layout of the primary coil, and wherein thelayout of the primary coil is located within a layout of the secondsecondary coil.